Celiac Screening: Who Should Get Tested?

Celiac disease is underdiagnosed. For every diagnosed celiac, there may be several undiagnosed ones walking around with vague symptoms or no symptoms at all.

Should you be tested? Should your family? Here’s how to think about it.

Who Should Definitely Be Tested

People with Symptoms

Classic GI symptoms:

• Chronic diarrhea
• Bloating and gas
• Abdominal pain
• Constipation (yes, constipation too)
• Nausea/vomiting

Non-GI symptoms also warrant testing:

• Unexplained anemia (especially iron-deficiency not responding to supplements)
• Chronic fatigue
• Bone or joint pain
• Unexplained weight loss
• Failure to thrive (children)
• Delayed puberty
• Short stature
• Dental enamel defects
• Recurrent mouth ulcers
• Dermatitis herpetiformis (itchy blistering rash)
• Peripheral neuropathy (numbness/tingling)
• Ataxia (balance problems)
• Brain fog/cognitive issues
• Depression or anxiety (especially with other symptoms)
• Elevated liver enzymes (unexplained)
• Infertility or recurrent miscarriage

Celiac is a chameleon. The symptoms are broad.

First-Degree Relatives of Celiacs

If you have a parent, sibling, or child with celiac:

• Your risk is ~10% (vs. 1% general population)
• Testing is recommended even without symptoms
• Screen periodically if initially negative (it can develop later)

People with Associated Conditions

Certain conditions increase celiac risk:

Autoimmune:

• Type 1 diabetes
• Autoimmune thyroid disease
• Autoimmune liver disease
• Sjögren’s syndrome

Genetic syndromes:

• Down syndrome
• Turner syndrome
• Williams syndrome

Other:

• IgA deficiency (actually makes testing harder but celiac is more common)

If you have these conditions, celiac screening makes sense.

Who Might Consider Testing

Vague or Non-Specific Symptoms

If you have:

• General malaise that won’t resolve
• “Something is wrong” that doctors can’t explain
• Symptoms that overlap with celiac

It’s worth testing. Celiac is often missed because symptoms don’t fit the classic picture.

IBS Diagnosis

Many people diagnosed with irritable bowel syndrome (IBS) actually have celiac:

• Symptoms overlap significantly
• Celiac should be ruled out before accepting IBS diagnosis
• If you have IBS and haven’t been tested for celiac, consider it

Family History of Autoimmune Disease

Even without a celiac diagnosis in the family:

• Autoimmune diseases cluster
• Family history of thyroid disease, type 1 diabetes, etc. suggests higher overall autoimmune risk

Testing Guidelines by Age

Children

With symptoms: Test as soon as symptoms present (usually after gluten has been in diet for some time).

First-degree relatives: Begin screening around age 2-3, once eating gluten regularly. Repeat periodically.

At-risk conditions: Screen when diagnosis of associated condition is made.

Adults

With symptoms: Test now.

First-degree relatives: Test at any age. One test may not be enough, celiac can develop throughout life.

At-risk conditions: Screen when risk is identified.

Older Adults

Celiac can be diagnosed at any age:

• Not just a childhood disease
• Late-onset celiac is common
• Symptoms may be attributed to aging when they’re actually celiac

The Testing Process

Step 1: Blood Test

tTG-IgA plus Total IgA is the standard first step:

• Minimally invasive
• Good sensitivity and specificity
• If positive, confirms need for further testing
• If negative (with normal IgA), celiac is unlikely

Step 2: Endoscopy with Biopsy

If blood tests are positive:

• Endoscopy to examine the intestine
• Biopsy to look for villous atrophy
• Still considered gold standard for diagnosis

Important: Be Eating Gluten

Tests only work if you’re eating gluten:

• Don’t start the GF diet before testing
• If already GF, you may need a gluten challenge (eating gluten for weeks before testing)

This is why testing before dietary changes is so important.

What If You’re Already Gluten-Free?

If you’ve been GF and want to know if you have celiac:

Option 1: Gluten Challenge

Return to eating gluten:

• Duration varies (often 6-8 weeks recommended)
• Eat significant gluten daily (equivalent to 2+ slices of bread)
• Then test

This is hard if gluten makes you feel terrible. Discuss with your doctor.

Option 2: Genetic Testing

HLA-DQ2 and DQ8 testing:

• Doesn’t require eating gluten
• Can rule OUT celiac if negative (you lack the required genes)
• CANNOT confirm celiac if positive (just shows you could develop it)

If genes are negative: celiac is virtually impossible If genes are positive: need further testing that requires gluten

Option 3: Accept Uncertainty

Some people:

• Know gluten makes them sick
• Can’t face a gluten challenge
• Accept that they’ll never have a formal diagnosis

This is a valid choice, though it has limitations (family testing, insurance, future research participation).

The Case for Testing (Even Without Symptoms)

Why Test First-Degree Relatives

Even without symptoms:

• Silent celiac damages intestines
• Long-term complications develop silently
• Earlier detection means earlier treatment
• Prevents future problems

Why Not Just Try GF?

Before trying the diet:

• Test first
• A diagnosis has value (family implications, insurance, research)
• Once you’re GF, diagnosis becomes much harder

After a Negative Test

If testing is negative:

• Celiac is unlikely (assuming you were eating gluten)
• Consider other diagnoses for symptoms
• For high-risk individuals, may be worth retesting later (celiac can develop over time)

The Takeaway

Who should be tested:

• Anyone with symptoms (GI or non-GI) that could be celiac
• First-degree relatives of celiacs
• People with associated autoimmune conditions or genetic syndromes

When:

• Before going gluten-free
• While eating adequate gluten
• Periodically for at-risk individuals if initially negative

Why:

• Celiac is common and underdiagnosed
• Treatment (GF diet) is effective
• Untreated celiac has consequences
• Diagnosis matters beyond just diet

If testing makes sense for you, talk to your doctor. A simple blood test can change everything.